PREDICTING INSULATION AND STRUCTURAL RESPONSE

OF FOAMED CONCRETE PANEL

SHANKAR GANESAN

UNIVERSITI SAINS MALAYSIA

2015

PREDICTING INSULATION AND STRUCTURAL RESPONSE

OF FOAMED CONCRETE PANEL

By

SHANKAR GANESAN

Thesis submitted in fulfillment of the requirements

for the degree of Master of Science

July 2015

ii

ACKNOWLEDGEMENT

I am extremely obliged to a great number of individuals that I wish to acknowledge.

Without their guidance and support, the completion of this research would have been

seemingly impossible. First and foremost, I would like to express my heartiest

gratitude to my supervisor, Dr. Md Azree Othuman Mydin for his never ending

support, invaluable guidance, patience, knowledge and constant motivation and

inspiration in completing this thesis. Also, I am really grateful to my co-supervisor,

Dr. Hanizam Awang for her co-operation, good guidance, great ideas and

encouragement throughout the study.

Acknowledgement is also addressed to the funding body of my M.Sc. studies,

Ministry of Higher Education Malaysia.

My thanks also goes to all the academic members and staff of the School of Housing

Building and Planning who has assisted me and shared their experience throughout

the experimental section of this research. Not forgetting, I owe a debt of thanks to

School of Biology and School of Materials and Mineral Resources Engineering,

USM for their participation in providing test facilities. Not only that, I also would

like to acknowledge the research officer of Forest Research Institute Malaysia

(FRIM), Mr. Khairul Azmi who guided and helped me throughout the fire resistance

test.

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I would like to give my sincere and immense gratitude to my lovely parents Mr.

Ganesan Muthusamy and Mrs. Ramadevi Ganesan, my brothers, Sathiswaran

Ganesan and Dhanesh Nair Mathavan, and my sisters Daarshini Paneerselvam and

Kalaivaani Ganesan for their unconditional love and morale-boosting. Not forgetting,

special appreciation to my beloved friend Ms. Janani Selvaraju for her love and

support throughout these years. Last but not least, without the mercy of Almighty, I

would not have been reached to this stage, hence all praise goes to Him.

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TABLE OF CONTENTS

PAGE

Acknowledgement ……………………………………………………………….. ii

Table of Contents ………………………………………………………………… iv

List of Tables ……………………………………………………………………... vii

List of Figures …………………………………………………………………….. ix

Abstrak .………………………………………………………………………….. xiii

Abstract …………………………………………………………………………… xiv

CHAPTER 1 – INTRODUCTION

1.1 Introduction ……………………………………………………………… 1

1.2 Problem Statement ………………………………………………….…… 4

1.3 Objectives of Research ………………………………………………….. 6

1.4 Significance of Research ………………………………………………... 6

1.5 Scope of Study …………………………………………………………... 7

1.6 Thesis Organisation ……………………………………………………… 9

CHAPTER 2 – LITERATURE REVIEW

2.1 Introduction to Lightweight Foamed Concrete (LFC) ……………………. 11

2.1.1 Advantages and Disadvantages of LFC ………………………….. 14

2.1.2 Applications of LFC ……………………………………………… 15

2.2 Constituent Materials of LFC …………………………………………….. 18

2.2.1 Ordinary Portland Cement ………………………………………... 18

2.2.2 Sand ………………………………………………………………. 19

2.2.3 Water ……………………………………………………………… 20

2.2.4 Foaming Agent …………………………………………………… 20

2.2.5 Additives ………………………………………………………….. 22

2.3 Curing …………………………………………………………………….. 27

2.4 Design Procedures and Methods of LFC Production …………………….. 28

2.5 Relevant Studies on Properties of LFC ……………………. …………….. 29

2.5.1 Compressive strength ……………………………………………... 29

2.5.1.1 Cement Sand Ratio ……………………………………….. 31

2.5.1.2 Water Cement Ratio ……………………………………… 31

2.5.1.3 Pore Distribution …………………………………………. 32

2.5.1.4 Curing Condition …………………………………………. 33

2.5.1.5 Additives ………………………………………………….. 33

2.5.2 Flexural Strength & Splitting Tensile Force ……………………… 37

2.5.3 Water Absorption of LFC ………………………………………… 39

2.5.4 Porosity & Permeability ………………………………………….. 41

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2.5.5 Thermal Properties ……………………………………………….. 45

2.5.6 Fire Resistance Performance ……………………………………... 50

2.5.7 Structural Response ………………………………………………. 53

2.6 Summary………………….………………………………………………. 58

CHAPTER 3 – METHODOLOGY

3.1 Introduction ……………………………………………………………….. 60

3.2 Constituent Materials ……………………………………………………… 61

3.2.1 Cement ……………………………………………………………. 61

3.2.2 Fine Aggregates (Sand) …………………………………………….62

3.2.3 Water ……………………………………………………………… 62

3.2.4 Foaming Agent ……………………………………………………. 63

3.2.5 Additives …………………………………………………………... 64

3.3 Experimental and Investigation Analysis …………………………………. 65

3.4 Experimental Study on the Mechanical and Engineering

Properties of LFC …………………………………………………………. 67

3.4.1 Slump Test ………………………………………………………… 68

3.4.2 Compressive Strength Test ……………………………………….. 69

3.4.3 Flexural Strength Test ……………………………………………. 70

3.4.4 Splitting Tensile Strength Test …………………………………… 71

3.4.5 Water Absorption Test ……………………………………………. 72

3.4.6 Porosity ……………………………………………………………. 72

3.4.7 Curing Regime ……………………………………………………. 73

3.5 Thermal Conductivity Test ……………………………………………….. 74

3.6 Fire Resistance Test ………………………………………………………. 76

3.6.1 At the Preliminary Stage/ Design ………………………………... 77

3.6.2 At the Casting Stage ……………………………………………… 79

3.6.3 At the Final Stage/Fire test ……………………………………….. 83

3.7 Structural Performance Test ………………………………………………. 85

CHAPTER 4 – EXPERIMENTAL INVESTIGATION AND ANALYSIS ON

THE PROPERTIES OF LIGHTWEIGHT FOAMED CONCRETE (LFC)

4.1 Introduction ………………………………………………………………. 88

4.2 Compressive Strength ……………………………………………………. 88

4.2.1 Effect of Density on the Compressive Strength of LFC …………. 89

4.2.2 Effect of Various Additives on the Compressive Strength of LFC... 92

4.3 Flexural Strength ………………………………………………………… 101

4.4 Splitting Tensile Strength ………………………………………………... 110

4.5 Water Absorption ……………………………………………………….. 118

4.6 Porosity of LFC ………………………………………………………….. 123

4.7 Thermal Properties of LFC ………………………………………………. 126

4.7.1 Thermal Conductivity at Different Densities …………………….. 127

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4.7.2 Thermal Diffusivity at Different Densities ………………………. 130

4.7.3 Specific Heat Capacity at Different Densities …………………… 131

4.7.4 Thermal Properties of LFC at Different Types of Additives …….. 133

4.8 Summary …………………………………………………………………. 140

CHAPTER 5 – STRUCTURAL AND FIRE RESISTANCE PERFORMANCE

OF LFC WALLING SYSTEM

5.1 Introduction ………………………………………………………………. 141

5.2 Structural Performance of Prototype LFC Walling System …………….. 142

5.2.1 Compressive Strength ……………………………………………. 144

5.2.2 Mode of Failure ………………………………………………….. 148

5.3 Fire Resistance Performance of the LFC Walling System ………………. 157

5.3.1 Fire Resistance …………………………………………………… 159

5.3.2 Surface Condition after Exposure to Fire …………………………167

5.4 Summary...…………………………………………………………………171

CHAPTER 6 – CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE

WORKS

6.1 Summary and Conclusions ………………………………………………..174

6.1.1 Mechanical properties and durability of LFC by incorporating

various types and percentages of additives………………………...175

6.1.2 Thermal properties of LFC with the addition of different types

and percentages of additives……………………………………….177

6.1.3 The fire resistance performance and structural behaviour of LFC

Wall panel………………………………………………………….177

6.2 Recommendations for Future Research Studies …………………………..178

REFERENCES ………………………………………………………….............. 181

ACKNOWLEDGEMENT ...………………………………………………………200

APPENDICES..……………………………………………………………………201

vii

LIST OF TABLES

PAGE

Table 2.1 Advantages and disadvantages of LFC 15

Table 2.2 Applications of LFC with different densities 16

Table 2.3 Studies done previously by many researchers on the mixes,

compressive strengths and density ranges of LFC

30

Table 2.4 The minimum thickness requirement for fire resistance ratings 52

Table 3.1 The properties of selected additives 64

Table 3.2 LFC sample with different additives and percentages 67

Table 3.3 Mix design of LFC wall panels 80

Table 4.1 Compressive strength of control LFC with different densities at

different ages

90

Table 4.2 The compressive strength of LFC with various fibres 94

Table 4.3 The compressive strength of LFC with various pozzolanic

materials

95

Table 4.4 The flexural strength with different densities 102

Table 4.5 The effect of addition of fibres on the flexural strength 103

Table 4.6 The effect of addition of pozzolanic materials on the flexural

strength

104

Table 4.7 Effect of various densities on the splitting tensile strength 111

Table 4.8 Effect of various fibres on the splitting tensile strength 112

Table 4.9 Effect of various pozzolans on the splitting tensile strength 113

Table 4.10 Water absorption of LFC of different densities 119

Table 4.11 Thermal properties of LFC with different densities 128

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Table 4.12 Thermal properties of LFC samples with different types of

additives

134

Table 5.1 Compressive strength of the samples 144

Table 5.2 The unexposed surface temperatures of control LFC wall panel 161

Table 5.3 The unexposed surface temperatures of FRLFC 162

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LIST OF FIGURES

PAGE

Figure 2.1 Air voids in 500kg/m3 (left) and 1000kg/m3 (right) 14

Figure 2.2 Relationship of dry density and the 39

Figure 2.3 Pore formations at two different densities 48

Figure 2.4 Details of prototype composite walling 56

Figure 2.5 Geometrical details of LFC sandwich panels 57

Figure 3.1 Portafoam TM1 foam generator system 63

Figure 3.2 Slump test 68

Figure 3.3 The sample being tested by the compressive machine 69

Figure 3.4 Four point flexural test 70

Figure 3.5 Setup of a cylindrically shaped specimen for tensile test 71

Figure 3.6 Equipment for porosity test 73

Figure 3.7 Sealed curing condition 74

Figure 3.8 The schematic view of Hot Disk Thermal test 75

Figure 3.9 LFC Samples and the Hot Disk Thermal Constant Analyzer 76

Figure 3.10 Sketch-up design of a major LFC wall panel 78

Figure 3.11 Plan view of LFC wall panel 78

Figure 3.12 Wooden moulds for LFC wall panels 79

Figure 3.13 LFC Sub-panel in drying process 81

Figure 3.14 Fully dried sub-panel 82

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Figure 3.15 Wall panel after combined the two sub-panels 82

Figure 3.16 Infill process 82

Figure 3.17 Wrapped wall panel 82

Figure 3.18 The arrangement of LFC wall panel during fire test 83

Figure 3.19 Fire formation inside the furnace 84

Figure 3.20 The thermocouples fixed on the unexposed LFC wall panel 86

Figure 3.21 The prototype of LFC sub-panel and joined wall panel 86

Figure 3.22 Prototypes of LFC wall panel after curing process 87

Figure 3.23 Compressive test on prototype of LFC wall panel 87

Figure 4.1 Relationship between density and compressive strength of

LFC at different ages

90

Figure 4.2 Percentage of porosity at different densities 91

Figure 4.3 Compressive strength of LFC with fibres 94

Figure 4.4 Compressive strength of LFC with pozzolanic materials 95

Figure 4.5 The flexural strength of LFC with various types of fibre 103

Figure 4.6 The flexural strength of LFC with various types of pozzolans 104

Figure 4.7 The internal surface of the LFC sample with CF-0.4 105

Figure 4.8 Internal surface of the LFC sample with PFA-30 107

Figure 4.9 The splitting tensile strength of LFC with various types of

fibres

112

Figure 4.10 The splitting tensile strength of LFC with various types of

pozzolans

113

Figure 4.11 Development of cracks formed on the LFC sample during

tensile strength test

115

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Figure 4.12 Effects of various types of additives on water absorption of

LFC at 28 days

120

Figure 4.13 Effects of various additives on the value of porosity 124

Figure 4.14 Relationship between density and thermal conductivity 129

Figure 4.15 Thermal diffusivity-porosity relationship 131

Figure 4.16 The morphology of coir fibre 135

Figure 4.17 Thermal conductivity of LFC sample with different types of

additives

139

Figure 5.1 Overview of prototype of LFC wall panel 143

Figure 5.2 Front elevation of wall panel test up for structural

performance

143

Figure 5.3 The transformation of the cracks during failure mode on the

control specimen

146

Figure 5.4 Small cracks on the surface of the FRLFC 146

Figure 5.5 The load (N) versus strain graph control wall panel &

FRLFC

148

Figure 5.6 (a) Cracks on the side and (b) middle surface of the control

specimen

150

Figure 5.7 (a) Cracks on the side and (b) middle surface of FRLFC after

failure

150

Figure 5.8 (a) Small cracks on the surface of FRLFC (b) Wide cracks

on control specimen

151

Figure 5.9 The condition of infill material of control LFC wall panel 153

Figure 5.10 The condition of the infill material of FRLFC 153

Figure 5.11 The sample without any mechanical connectors 154

Figure 5.12 The bonding between fibres and particles in infill 155

Figure 5.13 The bonding of infill material without any reinforcement 155

Figure 5.14 The condition of control sub-panel after dismantling 156

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Figure 5.15 The condition of FRLFC sub-panel after dismantling 157

Figure 5.16 Overview of a big scale of LFC wall panel 158

Figure 5.17 Thermocouples fixed at marked point on the surface of the

panel

160

Figure 5.18 Actual furnace temperature/time curve of control LFC wall

panel

163

Figure 5.19 Actual furnace temperature/time curve of FRLFC 164

Figure 5.20 The graph of temperature (ºC) against time (min) of control

specimen

165

Figure 5.21 The graph of temperature (ºC) against time (min) of FRLFC 165

Figure 5.22 Surface condition of exposed side of FRLFC 168

Figure 5.23 Surface condition of exposed side of control specimen 168

Figure 5.24 Surface condition of unexposed side of FRLFC 170

Figure 5.25 Surface condition of unexposed side of control specimen 170

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MERAMALKAN PENEBATAN DAN TINDAK BALAS STRUKTUR DALAM

PANEL KONKRIT BERBUSA

ABSTRAK

Konkrit ringan berbusa (LFC) dihasilkan daripada mortar atau campuran

simen berserta gelembung udara yang dihasilkan daripada agen campuran tertentu.

Penggunaan LFC sebagai bahan binaan menjadi prerogatif dalam industri pembinaan

kerana ia memiliki banyak kelebihan seperti lebih ringan, kekuatan rendah dikawal

dan sifat haba yang sangat baik. Kajian ini memberi tumpuan kepada sifat-sifat LFC

dengan pelbagai bahan campuran dan ketumpatan serta potensi sistem panel dinding

LFC dari segi prestasi ketahanan struktur dan api. Tiga jenis ketumpatan (700, 1000

dan 1400 kg/m3) dengan campuran pelbagai bahan campuran (abu bahan api

terhancur, abu kayu, abu bahan bakar minyak sawit, silica, fiber polipropilena, fiber

keluli dan fiber sabut) telah disiasat. Kekuatan mampatan, kekuatan lenturan,

kekuatan tegangan, penyerapan air, keliangan dan sifat haba adalah sifat-sifat yang

diukur. Fiber sabut menunjukkan peningkatan yang sangat baik dari segi sifat

mekanikal dan terma disebabkan oleh struktur molekul dalaman LFC. Fiber sabut

dengan jumlah yang banyak telah terbukti agar mampu menghalang lebih banyak air

daripada merentasi sampel LFC. LFC yang ketumpatan rendah menyumbang kepada

sifat penebat terma yang baik akibat daripada keberkesanan dalam konduktiviti

terma. Panel dinding LFC dengan fiber (FRLFC-prototaip) dengan saiz 0.3m x 0.3m

dan ketebalannya 0.15m menunjukkan peningkatan sebanyak 27% di bawah

mampatan paksi berbanding dengan sampel kawalan kerana campuran fiber

mempunyai ketahanan yang kuat di bawah mampatan paksi. FRLFC (1.5m x 0.675m

dan ketebalannya 0.15m) juga mempunyai keupayaan untuk mengurangkan kadar

pemindahan haba kerana ia telah mempamerkan kapasiti haba yang tinggi.

xiv

PREDICTING INSULATION AND STRUCTURAL RESPONSE OF

FOAMED CONCRETE PANEL

ABSTRACT

Lightweight foamed concrete (LFC) is produced by mortar or cement paste in

which air-voids are entrapped in the mortar by means of suitable foaming agent.

Demand and usage of LFC as building material become privileged in construction

industry due to many advantages such as lighter weight, controlled low strength and

excellent thermal properties. This research mainly focuses on the properties of LFC

with various densities and additives with different percentages and also the potential

application of LFC wall panel system in terms of structural and fire resistance

performance. Three different densities of 700, 1000 and 1400kg/m3 with various

additives (Pulverized fuel ash, wood ash, palm oil fuel ash, silica fume,

polypropylene fibre, steel fibre and coir fibre) were cast and investigated.

Mechanical strength, durability and thermal properties were measured. Coir fibre

showed an excellent improvement in the mechanical and thermal behaviour

compared to other additives due to its internal molecular structure of the LFC. A high

amount of coir fibre is proven to be able to inhibit more water from migrated through

LFC specimen. Low density of LFC provided the best thermal insulation properties

due to its effectiveness in thermal conductivity. Fibre reinforced LFC wall panel

(FRLFC-prototype) with 0.3m x 0.3m and thickness of 0.15m showed an

improvement of 27% under axial compression in comparison to the control sample

because the fibre has strong resistance under axial compression. FRLFC (1.5m x

0.675m and thickness of 0.15m) also has the ability to diminish the rate of heat

transfer because it has improved the interfacial adhesion between fibres and the

matrix and exhibited high heat capacity.

1

CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION

In today’s society, the advancement in construction industry plays an important role

to discover the latest methods and technologies for the future. Traditional technology

which utilizes conventional method in producing normal weight concrete has been

established and being in use up to now. It is used for different applications in

construction such as architectural structures, wall partitions, foundations, runaways

and highways. However, new innovative materials that can cater for different

construction purposes are significant these days. The selection of proper building

materials has to be done in order to minimize energy usage in buildings. In addition,

particular attention should be given to thermal insulation and fire resistance

properties because low thermal conductive materials will enhance the thermal

comfort of indoor environment.

In conjunction with that issue, the construction industry is seeking for a new building

structure which will able to function as a thermal barrier, prevent heat and fire

spread. Designing fire-proof building structures is constantly attracting more

attention and of great importance. As a remedy for unforeseen circumstances due to

uncontrolled fire, the construction industry is gradually switching their interests

towards the use of lightweight foamed concrete (LFC) instead of using traditional

concept building materials due to many advantageous characteristics such as being

2

lighter in weight, as excellent thermal and acoustical insulation, is easy to fabricate,

durable, minimal consumption of aggregates and cost effective. These noticeable

qualities indicate its strong potential as a valuable material in building construction

to increase indoor thermal comfort by reducing heat absorption.

LFC is described as a cementitious material with at least of 20 per cent by volume of

mechanically entrained foam added to a cement paste or slurry (Van Deijk, 1992) in

which air voids are entrapped by means of suitable foaming agent. LFC is also

known as porous concrete. The most basic definition of foamed concrete is that

“mortar with air bubbles”. The air content is almost 75% by volume of the cement

paste. LFC consists of Portland cement paste or cement filler matrix with

homogeneous pore structure together with sand, water and foaming agent. LFC can

be produced in a wide range of densities from 400 kg/m3 to 1600 kg/m3 by properly

controlling the quantity of foam added to the cement paste and its compressive

strength ranging from 0.5 – 10N/mm2 respectively (Aldridge, 2005).

LFC is not a new material in the construction industry and surprisingly it has a long

history. It was patented first in 1923 (Valore, 1954) and its usage was very limited

until 1970. The Romans had used air entrainers to decrease density. Moreover, LFC

was mostly used as an insulation material and its application as semi-structural

lightweight material has increased after a few years. It was first applied in

Netherlands for ground engineering and for void filling works and in the United

Kingdom, a full-scaled assessment on the application of lightweight concrete as

trench reinstatement was carried out in 1987. LFC can be laid down easily and it

does not require compaction, vibrating or leveling. LFC can be used as a partition or

3

light load bearing walls in low rise building although the mechanical properties of

foamed concrete is low when compared to normal weight concrete.

The density and the mechanical properties are inversely proportional to the

percentage of porosity of LFC. On the other hand, thermal conductivity of LFC is

also influenced by the density of constituent materials in the mortar slurry.

Therefore, the thermal conductivity can be reduced by replacing cement with finer

particles such as fly ash and silica fume. The ingredients used to cast LFC into a

desired shape are similar to that of conventional concrete. Foaming agent is used to

generate foam with the aid of foam generator machine to substitute the place of

aggregates. The contributions of LFC in speeding up the building rates and reducing

the dead load of structural elements are essential for current building industry.

Due to its fluidity, it can be poured into various shapes and sizes to fulfill current

worldly building design structures. Although LFC possess many attractive

characteristics, its mechanical properties are lower compared to that of normal

weight concrete. Previous studies that have been conducted by many researchers

have sorted out this issue and it has been proven that LFC still can be used as a

structural element in buildings. This experimental study is divided into two main

stages. The first stage is to a conduct pilot study on the properties of LFC. At this

stage, a detailed study and investigation were carried out to look into the properties

of LFC with different densities and additives. The results from the investigations will

be used for further applications. In the second phase, experiments are performed to

observe fire resistance and structural performance of LFC wall panel in a big scale

by means of suitable procedure and equipment.

4

1.2 PROBLEM STATEMENT

In construction industry, providing a system to control fires is a great implication of

engineering practice because uncontrolled fires can cause serious injuries, fatalities

and economic loss. Typical practice in fire protection is making compartments in

building using fire resistant barriers in order to prevent fire from spreading to other

areas. As mentioned earlier, discovering building structures against fire is constantly

attracting more attention and is of great significance. Therefore, it is necessary for

the construction industry to shift its importance towards the use of LFC due to

excellent fire resistance properties and acoustical insulation compared to that of

conventional concrete. Not only that, the demand is increasing because of its some

other notable characteristics such as low self-weight, durability, and cost effective.

However, the major problem with LFC is its lower strength compared to normal

weight concrete. Therefore, it has constructed a barrier for further applications in

building construction though it contributes to excellent thermal insulation. The

addition of some materials as additives into mortar slurry has a potential to enhance

the mechanical properties of LFC. Previously, only a few researches have been

conducted to look into the effects of additives on the strength of LFC. Sustainability

is the serious issue all over the world. Releasing of carbon dioxide has been a severe

problem in the world due to greenhouse effect. The use of cement replacement and

other abundant materials with optimum content of cement and enhancement of

concrete durability are the main issue towards sustainability in concrete industry. The

study of fire resistance performance of any structural element is of great significance,

more so for a new and innovative material like LFC. However, quantitative

5

information on fire resistance performance of LFC is extremely sparse. According to

Jones and McCarthy (2005), a majority of researchers previously have just focused

on the mechanical properties and only a few on thermal properties of LFC.

As mentioned earlier, the construction industry is searching for a building material

which has good fire insulation and is potential to be a load bearing structure in

buildings. Therefore, studies on the fire resistance and structural performance of LFC

are required to provide more knowledge on the subject of LFC. Unfortunately, no

studies have been conducted on the effect of additives on fire resistance and

structural performance of LFC wall panel. As a conclusion, this research focuses on

the properties of LFC with different types and percentages of additives to enhance

further its mechanical and thermal properties. This stage is to obtain reliable thermal

and mechanical properties for quantification of its fire resistance performance and

some indication whether it has enough load bearing performance. Then, as main

activities of this research the structural behaviour and fire resistance performance of

LFC wall panel under axial compression and fire test were examined respectively to

conclude the potential of LFC for the application as a load bearing structure in

building construction. The use of additive in LFC wall panel is to reinforce the

structure and to provide better thermal properties. The findings from this research

will address the knowledge gap in the subject of LFC and will provide an improved

understanding and raised awareness of the fire resistance performance of LFC based

system.

6

1.3 OBJECTIVES OF RESEARCH

The main objectives of this study are:

i. To investigate the mechanical properties and durability of LFC by

incorporating various types and percentages of additives.

ii. To determine the thermal properties of LFC with the addition of different types

and percentages of additives

iii. To observe and determine the fire resistance performance and structural

behaviour of LFC wall panel.

1.4 SIGNIFICANCE OF RESEARCH

LFC is relatively a new innovative building material in the construction industry.

Lack of knowledge on the performance of material is the main reason which restricts

the usage of LFC in applications. This research will provide a detailed understanding

with comprehensive justification on the properties of LFC to promote its demand in

the construction industry. In order to quantify the performance of LFC based system,

mechanical and thermal properties must be made known earlier. Furthermore,

knowledge of thermal properties of LFC with additives at ambient temperature is

essential to quantify its fire resistance performance. Its significant values such as

thermal conductivity, specific heat, porosity and density must be taken into

consideration in determining thermal properties of LFC.

7

The temperature in the structure must be determined in order to predict the building

structure’s fire resistance. Besides that, compressive, flexural and tensile strength

must be established to demonstrate whether it has adequate load bearing capacity.

The utilization of some additives in this study is predicted to enhance the durability

of the concrete and thus it will indirectly offer a better understanding to future

researchers who been working in the field of foamed concrete technology. The

proposed design of LFC wall panel is expected to reduce the total weight of the

whole panel. It can be constructed quickly and easily owing to its low density

compared to that of normal weight concrete. Finally, this research will provide

detailed explanations on the structural and thermal properties of LFC and will

promote it to be a building material for low rise construction.

1.5 SCOPE OF STUDY

This present research will cover the thermal, mechanical and durability properties of

LFC. For this study, LFC specimens with different densities (700kg/m3, 1000kg/m3

and 1400kg/m3) were prepared to observe the effects of different densities on their

mechanical and thermal properties. At the same time, specimens with different

additives were also cast at a density of 1000kg/m3 and observed to examine the

variations in the mechanical, durability and thermal insulation properties. Hardened

specimens such as cube (100x100x100mm), prisms (100x100x500mm) and cylinder

(100mm diameter and 200mm length) will be prepared and tested to look into the

thermal, mechanical and durable properties of LFC.

8

All specimens cast for this study will be sealed curing. This sealed curing regime is

advisable for low density LFC and it is better than water curing condition because

water curing method is unable to produce complete curing for low density samples of

less than 1000kg/m3 (water density). The cement-sand ratio, water-cement ratio, type

of cement and content, pore size and distribution, type of foaming agents and curing

regime are the main factors that influence the strength of LFC. Therefore, in this

research the water cement ratio is fixed at 0.45. Meanwhile, the cement sand ratio is

1:1.5 for all mixes. LFC wall panel will be designed and casted at the final stage of

this research to observe its structural response and fire resistance performance.

9

1.6 THESIS ORGANISATION

The chapters for this thesis will be organized according to their sequence and each

chapter will describe its function in providing a detailed understanding of this overall

study. This research is organized in the following six chapters:

Chapter 1 presents a general introduction to the project and the thesis.

Chapter 2 provides relevant literature review on the properties of LFC, including its

application. Also in this chapter, the behaviour and reaction of each material

including the additives used for this study would be discussed briefly. Limitations in

the previous studies would be identified and further knowledge would be provided as

a platform for a better understanding of this project.

Chapter 3 explains comprehensively the methodology used in this study including

the experiments and investigations that were carried out. This chapter discusses the

overall experimental study of the properties of LFC. This section will provide clear

details on the design of LFC wall panel and the experimental setup for fire resistance

and structural performance test.

Chapter 4 discusses the results of the mechanical properties of LFC such as

compressive, flexural and splitting tensile strength and the durability test results such

as water absorption and porosity with three different densities and various

percentages of different additives. Detailed investigations were conducted in relation

to several aspects such as the characteristics and the reaction of additives and

10

hydration process. In addition, this chapter describes the thermal properties of LFC

with three different densities and additives. Thermal tests were conducted by means

of Hot Disk Thermal Constant Analyzer and essential values such as thermal

conductivity, thermal diffusivity and specific heat capacity were recorded for further

analysis.

Chapter 5 presents experimental results on fire resistance and structural

performance of LFC wall panel. The best additive selected from the analysis of

mechanical and thermal properties results presented in Chapter 4 would be discussed.

This chapter will discuss both controlled and fibre reinforced LFC wall panels that

experimented to evaluate their potential under fire and structural test.

Chapter 6 summarizes the results obtained from this study and proposes

recommendations for further research studies to gain an extensive knowledge of

LFC.

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CHAPTER 2

LITERATURE REVIEW

The main aim of this research is to experimentally investigate the properties of

lightweight foamed concrete (LFC) with several additives and its performance in

terms of structural and fire resistance. This study is expected to fulfill the knowledge

gaps in the field of fire resistance performance of LFC based system. This chapter

will review the literature on the properties of LFC, including its mechanical

(compressive, flexural and tensile), durability (porosity, water absorption and

microstructure) and thermal performance. This input will provide a better

understanding on the utilization of LFC in lightweight walling system. The results

and findings of previous researches would be reviewed and analyzed thoroughly in

order to obtain fundamental properties so as to produce a better outcome at the end of

this experimental investigation for the application of LFC as building material in the

construction industry.

2.1 INTRODUCTION TO LIGHTWEIGHT FOAMED CONCRETE (LFC)

LFC is a cementitious material which consists of components such as sand, ordinary

Portland cement, water and stable foam. Aggregate is one of the main constituent

materials for conventional concrete which will be replaced by foam in the making of

LFC. A metered volume of preformed foam was incorporated to entrain air voids

into a cement paste or mortar mix. The preformed foam is developed in the foam

generator machine from foaming agent mixed with water and air. This foam plays a

12

vital role in changing the density of LFC by inhibiting millions of evenly distributed,

consistently sized bubbles. Foam can be concluded as an expanding agent which can

promote the volume of slurry mix while increasing some extra properties. According

to Aldridge (2005), the term of LFC is itself misleading because the majority of

western LFC contain no large aggregates. It consists of only fine sand, cement, water

and foaming agent. Therefore, the final products should be described with the right

term which is foamed mortar. According to Van Deijk (1992), LFC is specially

manufactured containing a minimum of 20 per cent by volume of air with pre-formed

foam or foaming agent incorporated into a cementitious base mix. During the

mixing, placing and hardening process of the concrete, the stable air bubbles in the

foam are able to resist the imposed physical and chemical forces.

LFC was firstly introduced by the Romans in the second century and has a very

interesting history. It was already patented in 1923 (Valore, 1954). Therefore, LFC is

no longer a new material in the construction field. The usage of LFC was limited due

to lack of specialized materials and equipment until the late 1970s. In the late 1980s

and 1990s, development of research on LFC was carried out in Netherlands. The

Reinstatements of Openings in Highways (1996) helped in increasing the production

and broadening of the scope of application of LFC in UK in the last 19 years. Since

then, LFC as a building material has become widespread with its expanding

productions and various applications. In 1914, Swedes found that the addition of

aluminium powder could generate hydrogen gas in the cement slurry. It was lately

reported that LFC has been discovered in Europe over 60 years ago and it was more

than 20 years since it has been in the international market.

13

LFC is also known as porous concrete and it is noticeable because of its favorable

characteristics. It has highly flow ability, low self-weight, controlled low strength

and excellent thermal properties. Though LFC has very low strength compared to the

conventional concrete, it shows a positive response in terms of thermal and

acoustical properties. One of its interesting characteristics is that the density of LFC

can be changeable depending on its applications. Previous studies revealed that the

dry density of LFC is varied from 400kg/m3 to 1600kg/m3 and the range of

compressive strengths is from 0.5 – 10N/mm2 (Aldridge, 2005). It is 87% to 23%

lighter than the conventional concrete. According to Liew (2005), there are several

ways to reduce the density of concrete by using lightweight aggregates, foam, high

air concrete and no-fine aggregate. The LFC density depends on the amount of foam

added to the mixture by foam generator. It lessens the dead load by becoming lighter

when compared to conventional concrete.

The higher air content of the LFC will result in the lower density, higher porosity and

the decrease of strength. The size of the bubbles are typically 0.3-0.4mm diameter

enclosed by cement. The stability of foam is actually created by these bubbles in

foamed mortar. Meanwhile, the bubbles produced from the foam machine will

replace the coarse aggregates and will cause the reduction of the density and

compressive strength as well. The air voids in low density LFC are typically bigger

than in the high density because of the dosage of foam added. The high amount of

foam will generate more continuous and connected pores within the concrete but on

the other hand, less connected pores can be observed in high density as shown in

Figure 2.1.

14

Figure 2.1 Air voids in 500kg/m3 (left) and 1000kg/m3 (right)

(Wei et al., 2013)

2.1.1 Advantages and disadvantages of LFC

LFC has more advantages in terms of its properties compared to normal strength

concrete. It has faster building rate in construction industry and also the reduction of

dead load. Since LFC is lightweight, it has low handling cost and lower haulage. The

advantage of lower LFC density is excellent thermal conductivity which can give

better insulation properties in terms of fire resistance and sound absorption due to the

cellular microstructure (Ramamurthy et al., 2009). Aldridge and Ansell (2001) found

that thermal conductivity of LFC sample with a density of 1000kg/m3 is reported to

be one-sixth of the value of common cement-sand mortar.

The values of thermal conductivity are 5-30% of those recorded on normal weight

concrete and the range is between 0.1 W/mK and 0.7 W/mK for dry densities of 600-

1600kg/m3 (Jones and McCarthy, 2005). LFC is classified to be less efficient than

denser concrete in reducing the transmission of air-borne sound (Taylor, 1969).

Normal weight concrete tends to deflect sound waves but LFC absorbs it. Therefore,

it can be said that LFC has higher sound absorption capacity. Meanwhile, Valore

15

(1954) stated that this cellular concrete does not contain significant acoustic

insulation characteristic. On the other hand, LFC has its disadvantages as well as

shown in Table 2.1.

Table 2.1 Advantages and disadvantages of LFC (Source: Neville, 1985)

Advantages Disadvantages

Rapid and relatively simple construction Very sensitive with water content in the

mixture

Economical in terms of transportation as well as in

reduction of manpower

Difficult to place and finish because of the

porosity and angularity of the aggregate. In

some mixes, the cement mortar may

separate the aggregate and floats towards

the surface

Significant reduction of overall weight results in

saving structural frames, footing or piles

Most of lightweight concrete have better nailing

and sawing properties than stronger conventional

concrete

Mixing time is longer than that of

conventional concrete to assure proper

mixing

2.1.2 Applications of LFC

Basically, LFC can be used as structural components, non-structural partitions and

thermal insulating elements (Rudnai, 1963). In order to fulfill these requirements for

each application, various density of LFC must be developed. The range of density

(300kg/m3 – 1840kg/m3) plays an important role in the applications such as trench

reinstatement, bridge abutment, large void filling works, bulk filling, backfills for

retaining walls, insulation for foundations and roof tiles, pipeline infill and grouting

for tunnel works, sound insulation and sandwich fill for precast units. According to

Gao et al., (1997), drops in density of LFC with the same level of strength permits

the preservation of dead loads for structural design and foundation. The application

elements can be structural, partially-structural and non-structural and the LFC high

16

density product will be used as structural building elements. Meanwhile partially

structural elements will be occupied by medium density and low density material

will be for non-structural elements. Table 2.2 shows various applications of LFC

with different density.

Table 2.2 Applications of LFC with different densities,

(www.litebuilt.com)

Density Applications

Density 300-600kg/m3

(Made of cement & sand)

Used in roof and as insulation

against heat and sound

Interspace filling between

brickwork leaves

Insulation in hollow blocks and

any other filling situation

Density of 600-900kg/m3

(Made of sand, cement and

foam)

Manufacture of precast blocks

and panels

Slabs for false ceilings

Thermal insulation and

soundproofing screeds

Bulk fill application

Density of 900-1200kg/m3

(Made of sand, cement and

foam)

Used in concrete blocks and

panels for outer leaves of

buildings

Architectural ornamentation as

well as partition walls

Density of 1200-1600kg/m3

Made of sand, cement and

foam)

Used in precast panels of any

dimension for commercial and

industrial use

In-situ casting of walls, garden

ornaments and other use

17

LFC can be used as lightweight blocks or bricks for high rise building. Also, panels

and partitions can be produced by precast and cast in-situ from LFC. It can be used

for low cost terrace house, bungalows and low rise building construction as

partitions. According to Nooraini et al., (2009), the water absorption by LFC blocks

is lesser than that of the bricks, hence, it has a longer lifespan. Since LFC has good

thermal insulation properties, its contributions for the construction industry,

especially in insulation works, are mostly acceptable. Being low in weight and

having better thermal properties make LFC potential to be used in housing

applications. According to Jones and McCarthy (2005), LFC has already been used

as roofing insulation material in South Africa, however its low density influences the

creation of roof slopes.

Besides that, LFC has been used in the manufacture of support structure in mining

areas in South Africa and a research has been conducted on thermal resistant

performance in Ukraine. In Malaysia, the application of LFC as wall panel attracts

the attention of developers and is becoming popular within these 10 years. The major

application of LFC is SMART tunneling project in Kuala Lumpur. LFC was used to

shield the diaphragm wall when the tunneling machine was removed to the junction

box. In the Middle and Far East area, 3000 residential buildings were constructed

using LFC with a density of between 1100 to 1500 kg/m3 in 1948 and 1958. After 25

years, the buildings were assessed and it was found that these buildings required the

least maintenance compared to buildings constructed with contemporary timber or

bricks and concrete (Nooraini et al., 2009).

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2.2 CONSTITUENT MATERIALS OF LFC

LFC is produced from cement, fine sand, water and chemical agent (stable foam).

The next section will give brief discussion on the properties and requirements of each

material used for better understanding.

2.2.1 Ordinary Portland cement

Ordinary Portland Cement (OPC) is the main binder for the production of LFC.

Rapid hardening Portland cement (Kearsley and Wainwright, 2001) which contains

high alumina and calcium Sulfo-aluminate (Turner, 2001) are used to reduce the

setting time and to develop the initial strength of the LFC. In Ordinary Portland

cement, the main chemical components are limestone, alumina and silica which are

vital to form calcium silicate hydrate (CSH) gel during hydration process. The fine

inorganic element will form a paste called cement paste after water has been added

added to the mixture.

According to BS12:1996, ordinary Portland cement usually functions as the main

binder in LFC. Previously, most researchers had attempted to reduce the usage of

cement in LFC by replacing other materials as alternative due to their concern on the

sustainability aspect and wise. The study conducted by Kearsley and Wainwright,

(2001) revealed that cement can be replaced by fly ash, which is an industrial waste,

to enhance the properties of LFC by reducing the temperature during hydration

process.

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2.2.2 Sand

Sach and Seifert (1999) suggested only fine sand (BS 882:1992) or mortar (BS:

1200:1976) and particle sizes up to 4mm should be used for LFC. According to

Noordin (2000), the sand used for LFC should be fine with the sizes of between 0-

2mm because coarse aggregates may affect the stability of foam during the mixing

process. Higher strength of LFC attributes to the relatively uniform pore distribution

by using fine sand while mixtures with coarse sand will produce larger and irregular

pores. The types of sands that are usually used to produce LFC normally consist of

natural sand, manufactured sand or a combination of both.

Fine aggregates that are subjected wetting should not have any impurities that will

cause destructive reaction in the cement. It will result in excessive expansion and

will lead to the cracking of concrete. Fly ash can be partial or total replacement for

sand in order to produce LFC below 1400kg/m3 according to (BS 3892: Part 1:1997).

Fly ash is very fine particles than sand. If fly ash were to be replaced with sand, the

compressive strength of the LFC will therefore be increased. In a study, Nambiar &

Ramamurthy (2006) showed finer the filler, the higher the ratio of strength will be

achieved. The absence of aggregates will lead to shrinkage problem in LFC.

However, other materials can be used as a replacement of aggregates in order to

reduce the shrinkage problem.

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2.3 Water

Water plays an important role in producing workable concrete which will form into a

paste after being mixed with other materials. The PH value of water should be

between 6 to 8 which is not tested and the criteria of portability of water is not

absolute. The amount of water should be kept under control so as to reduce the

shrinkage in LFC after it has dried. The amount of cement in the mixture and use of

chemical admixtures will influence the amount of water added during the mixing.

Karl and Worner (1993) found that water requirement for a mixture should depend

on the consistency and stability of that mixture.

An appropriate amount of water is necessary to prevent the foam from being

damaged in the mix (Mydin, 2010). The compressive strength of the concrete may be

reduced by water containing algae in the mixing procedure because this will result in

air entrainment in the paste. Sea water is rich in chlorides which can be the major

cause of the corrosion of the reinforcement concrete. Neville and Brooks (2001)

stated that the water used in the mix composition must be clear and apparently clean.

Narayanan and Ramamurthy (2000) mentioned that low water content will cause the

mix to become too stiff thereby causing air bubbles to break up. The mix will be too

thin to hold the bubbles if a high amount of water is being added, thereby leading to

the segregation of bubbles.

2.2.4 Foaming agent

Foaming agent plays a vital role in the manufacturing of LFC. It is also known as

“air entraining agent” because the air bubbles inside LFC are produced by this

21

foaming agent. LFC can be produced by preformed foaming method and mixed

foaming method. Preformed-foaming method is the means of producing base mix

and stable foam and then blending them together. On the other hand, mixed foaming

method is where the foaming agent is mixed together with the base matrix and during

the process, foam is produced. In the early 1950’s, preformed foam was developed

by following the growth of foam generating materials that are highly refined from

stabilizers. The method has the potential to control the density effectively. In order to

develop the properties of conventional concrete, preformed foam is commonly added

to the cement paste to produce LFC. It can be split into two groups which are protein

based material and synthetic foaming agents.

It was found that pre-formed foam method is more beneficial than mixed foaming

method. Lower foaming agent is required in pre-formed technique and there is a

close relationship between air content in the mix and the amount of foaming agent

(Ramamurthy et al., 2009). Foaming agent can be classified as air entraining

surfactants which later will be incorporated into the cement paste. In order to resist

the pressure of a mortar until the cement takes its initial set, and strong bonding in

concrete is built up around the air pores, the foam added must be firm and stable

(Koudriashoff, 1949). The preformed method can be produced either on dry or wet

foam. Wet foam is produced by sprinkling a solution of surfactants over a fine mesh.

It has 2-5mm size bubbles and is relatively less stable. However, dry foam is

extremely stable and its bubbles size smaller than 1mm which makes it easily

applicable with the base material for generating a pump able LFC (Aldridge, 2005).

22

The properties of foam are mainly related to the quality of the foam. Synthetic

foaming agents are purely chemical solutions which are applicable to LFC density of

1000kg/m3 and they are very stable and very durable. The foam has finer bubbles

compared to protein based materials but it is generally contributes to low strength

especially at densities below 1000kg/m3 (Brady and Jones, 2001). According to Alex

Liew (2003), the ratio of protein based foam added to water is 1:30 to create discrete

bubble cavities in the mortar after being incorporated into it. The weight of protein

foam is between 60-80gram/liter. On the other hand, the weight of synthetic foaming

agent is only 40gram/liter. In order to produce stable foam practically, a portable

foaming generator will be purchased from the Malaysian Manufacturer

(www.portafoam.com).

2.2.5 Additives

This section is fully concerned with the characteristics of additives which can give

positive changes to LFC properties. Many researchers have studied several ways of

improving the properties of LFC by adding different materials as additives. There are

some additives with distinct behaviors which were found and investigated by

previous researches, to improve the properties of LFC. The additives can be added by

cement replacement or as the total volume of fraction because each additive used will

affect the characteristics of LFC in different ways. In fact, fly ash can be used as a

total or partial replacement for sand to produce LFC with noticeable strength below

dry density of 1400kg/m3 in accordance to BS 3892: Part 1: 1997. Fly ash is the

major by-product of industrial waste which can be obtained from exhaust gases of

coal-fire power stations and utilized as filler. It is also of great significance to

23

economy and the environment (Papadakis, 2000). According to Mehta and Monteiro

(2006), the utilization of fly ash in LFC has numerous advantages such as

minimizing greenhouse emission, providing better long term strength and durability,

lowering water content, reducing energy consumption and pressure on natural

resources.

According to Neville, (2005), high specific area of fly ash particles are able to react

with calcium hydroxide during the hydration process. The particles of fly ash

normally have a diameter of between 1µm and 100µm and the surface area between

250 and 600m2/kg. In addition, during cement hydration, the silicon oxide and

aluminium oxide of fly ash will react to calcium hydroxide to form additional

calcium silicate hydrate and calcium aluminate hydrate thereby forming a denser

matrix which will result in higher strength and better durability (Bendapudi, 2011).

High percentages of ash in LFC will reduce early compressive strength due to

pozzolanic reaction during the early stage of hydration process. The hydration

process transforms the complex particles from different sizes and shapes to another

form at different phases (Hanizam et al., 2012). The reaction of fly ash in hydration

will be completed after 150 days according to Narayanan and Ramamurthy (1999).

The sphere particle is then transformed into some prismatic members with semi-

crystalline gel.

According to Tay and Show (1995) and Tangchirapat et al., (2009), palm oil fuel ash

(POFA) is considered as a cement replacement in LFC mixing because of the

pozzolanic properties. According to MPOB (2010), approximately 61.1 million

tonnes of solid waste by-products in the form of fibers are produced which is about

24

70% of fresh fruit bunches being processed. POFA contains a high amount of silicon

dioxide in amorphous form which can produce calcium silicate hydrates gel (CSH)

when it reacts together with calcium hydroxide generated from the hydration process

(Karim et al., 2011). However, Eldagal (2008) stated that the products of pozzolanic

reaction cannot be obtained from primary cement reaction. The unprocessed POFA

particles have angular shapes and porous structures (Hussin et al., 2010) and the

water absorbed by porous POFA particles do not contribute to the flow ability of the

LFC mix but reduce fluidity.

Silica fume is known as micro silica which is a by-product of the production of

silicon and ferrosilicon alloys which releases silicon oxide during the process. This

can be oxidized to form them into very fine spherical particles of SiO2 (Sipple,

2009). This process will accelerate the reaction with calcium hydroxide produced

during the hydration of cement due to the presence of small highly reactive silica

particles. Small silica particles are capable of filling up the empty spaces between

cement particles due to free water, thus they will improve strength. Silica fume

contains very fine vitreous particles with the surface area ranging from 13,000 to

30,000m2/kg (Sipple, 2009). Each particle of silica fume is approximately 100 times

smaller than cement particles. Luther (1990), stated that silica fume is a highly

effective pozzolanic material due to the large content of fine silica. Neville (2005)

stated that the reduction in size and amount of capillaries is able to reduce the

permeability of the concrete.

Wood ash is categorized as a replacement for filler but it does not have high

pozzolanic properties as fly ash, silica fume or POFA (Abdullahi, 2006). The total